It would be great if we could keep an up to date national register of all the good chimney sweeps around the country but as you can imagine this is a somewhat transient profession and so a call through the good old yellow pages and an ask around some friends is usually the best course of action to get a sweep.
It is always worth asking them if they have done any local Pyro fires before and if so can they tell you where so you can ask the homeowner how it went, any doubts and we are always happy to give some tips to proactive chimney sweeps.